This invention relates generally to air valves and more particularly to air valves designed to minimize icing and improve efficiency for a reciprocating pump or the like. More specifically, this invention relates to an improved fluid operated, double diaphragm pump, and, more particularly, to the valve construction for such a pump.
The use of a double diaphragm pump to transfer materials is known. Typically such a pump comprises a pair of pumping chambers with a pressure chamber arranged in parallel with each pumping chamber in a housing. Each pressure chamber is separated from its associated pumping chamber by a flexible diaphragm. As one pressure chamber is pressurized, it forces the diaphragm to compress fluid in the associate pumping chamber. The fluid is thus forced from the pumping chamber. Simultaneously, the diaphragm associated with the second pumping chamber is flexed so as to draw fluid material into the second pumping chamber. The diaphragms are reciprocated in unison in order to alternately fill and evacuate the pumping chambers. In practice, the chambers are all aligned so that the diaphragms can reciprocate axially in unison. In this manner the diaphragms may also be mechanically interconnected to ensure uniform operation and performance by the double acting diaphragm pump. Exemplary pumps in this regard are shown and described in U.S. Pat. Nos. 4,854,832 and 5,584,666 (hereafter, “the '832 and '666 patents”), the specifications of which are incorporated herein by reference.
In designing air motor valving used to control the feed air to and exhaust air from the diaphragm chambers of such pumps, however, it is desirable to exhaust the diaphragm chambers as quickly as possible in order to obtain a fast switch over and high average output pressures. Large temperature drops are generated with such rapid exhausting of the diaphragm chambers, however, which cause the valve to become extremely cold and can cause ice formation from moisture in the exhaust air.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.